Clock base



FIG. 1 is a top, front and side perspective view showing the clock base of the new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is a right side elevational view thereof; and,

FIG. 7 is a left side elevational view thereof.

The broken-line showings of a clockwise and the dot-dash ground line in FIG. 1 are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a clock base, as shown. 